Compression, compaction, densification or sintering of powders are very common steps in powder material processing.
Powder material processing is important in, for example, the formation of structural ceramic components, electronic ceramic components (such as transducers, sensors, and batteries), metallic components (such as cermets and fuel cell electrodes), plastics, tabletted consumer goods (such as washing powders, nutraceuticals, and cosmetics), foods, agricultural products, veterinary products, crop products and pharmaceuticals (tablets).
In each of the above, compactability, compression, segregation and flow are key factors, and such factors depend on the surface property and shape of the particles in the powder.
Compacts such as material discs or tablets often comprise a number of additives in addition to one or more functional ingredients (hereafter host) which may be active ingredients or excipients. This is notably the case in tablets. The main additives include, but are not limited to: diluents or fillers; binders (which may be used to bind the powders together); disintegrants (which help the compacts to break up and dissolve); glidants (which are used to improve granule flow); anti-adherent or lubricants (which help the release of the compressed compact from the die); and anti-adhesives (which are sometimes used to prevent film residue being left on the die/punch). In addition, colourings, flavourings, sweeteners, buffers and adsorbents may be used.
Compacts are typically made by compressing a powder of particulate solid between two punches in a die of a compact press. For the ingredients to be transformed into compacts of satisfactory quality, the formulation must have the key attributes of suitable flow, fluidity and compressibility.
More specifically the powders used should have the following attributes:                Firstly, the formulation must flow into the die space of the press sufficiently rapidly and in a reproducible manner. Otherwise, unacceptable variation in compact weight, homogeneity in structure and content will ensue;        Secondly, the particles in the formulation must cohere when subject to a compressing force, and that coherence should remain after the compressive force has been removed; and        Thirdly, after the compression event is complete, it must be possible for the compact to be removed from the press without damage to either the compact or the press.        
Very few functional or active ingredients possess all three of these attributes in their original state, and indeed many possess none. Thus they require processing and subjection to treatments with other additive materials in order that the desired characteristics can be achieved.
Prior art identified, primarily in the ceramics field, include:
WO 2006/069614 which discloses a composite powder material comprising a hard particulate phase coated by cobalt or nickel;
JP 2006-241549 which discloses a metal tin fine powder having a fine particle diameter;
JP 2006 147959 which discloses magnetic powders containing small diameter soft magnetic metal powders of 10-80% by weight coated by an insulating material and bonding agent which are then press molded and hardened;
JP 60 118676 which discloses a hot pressing mixtures of ceramic powders and organic thermoplastic material;
KR 2005 0076148 which discloses copper coated amorphous powders of various metals; and
U.S. Pat. No. 4,079,441 which discloses tantalum powders with a particle core size from 30 μm to 2.5 μm.
All this prior art relates to the field of ceramics.
An object of this invention is to provide powders which have characteristics making them more suitable for compaction, a method of manufacturing such powders which is both simple and cost effective and compacts such as tablets which may be obtained from the powders of the invention.
In particular, it is concerned with pharmaceutical applications, particularly, though not exclusively, oral delivery, other solid dose forms which may be injected or implanted, as well as trans-dermal products such as patches and creams.